Is This Normal? · Hormone Therapy
The short answer on hot flashes on hormone therapy
Yes. Hot flashes and night sweats are among the most common side effects of tamoxifen and the aromatase inhibitors, and they can be frequent and intense. They often ease after the first year or two. You don't have to just put up with them in the meantime: several non-hormonal treatments have real evidence behind them, and your team can help you find one that fits.
What to know about hot flashes on hormone therapy
- You're in large company. The National Cancer Institute says about two-thirds of postmenopausal women with a history of breast cancer have hot flashes.
- Menopause can arrive overnight. Chemotherapy and ovarian suppression can bring it on suddenly, which can make symptoms hit harder.
- There are treatments that work. Venlafaxine, gabapentin and oxybutynin have each cut hot flashes substantially in trials.
- Some antidepressants don't mix with tamoxifen. Paroxetine and fluoxetine can weaken it, so tell every prescriber you take it.
- Don't quit quietly. Stopping hormone therapy early is linked to worse outcomes. Tell your team instead, because there are options.
Why does breast cancer hormone therapy cause hot flashes?
According to the American Cancer Society, tamoxifen blocks estrogen from attaching to cancer cells, while aromatase inhibitors (anastrozole, letrozole and exemestane) shut down most of the estrogen the body makes after menopause. The rest of your body notices either way.
The hot flashes that follow work the same way menopausal ones do. Dana-Farber describes them as brief, about four minutes, but intense: heat in the face, neck or chest, often with sweating, flushing or a racing heart. The NCI says night sweats affect about 44 percent of postmenopausal women with a history of breast cancer.
Tamoxifen can cause them even in women who still have periods. A 2023 review in the Journal of Menopausal Medicine says more than half of women on tamoxifen get them. It says symptoms usually improve after one to two years, and about 20 to 30 percent of women need medicine for a while.
Why are hot flashes worse when chemotherapy or ovarian suppression brings on sudden menopause?
For many younger women, hormone therapy isn't what started it. Chemotherapy can bring on early menopause. So can ovarian suppression, which uses medicine or surgery to shut down or remove the ovaries, the main source of estrogen before menopause. The American Cancer Society says every method of ovarian suppression puts the body into menopause and can cause its symptoms. Instead of easing in, you get the change abruptly, often with hormone therapy layered on top. If your hot flashes seem fiercer than what friends describe, that's part of why.
What other side effects of hormone therapy are normal?
Joint and muscle aches. These are a hallmark of aromatase inhibitors. The American Cancer Society says the stiffness can be bad enough that some women stop treatment. Options include switching aromatase inhibitors, exercise, anti-inflammatory pain relievers, duloxetine or acupuncture, or switching to tamoxifen to finish.
Vaginal dryness. Common with aromatase inhibitors, and it can make sex hurt. Moisturizers and lubricants are the usual first step. Ask your team what's safe for you, and read So, What Happens to Sex After Breast Cancer?
What actually helps hot flashes during breast cancer hormone therapy?
Hot flashes respond surprisingly well to placebos (in one trial the NCI cites, by 63 percent), so what counts is beating a placebo. These have.
Venlafaxine. An antidepressant (in a class called SNRIs) that the NCI says reduces hot flashes by about 55 to 60 percent. The British Menopause Society calls it the preferred choice for women on tamoxifen.
Other antidepressants, with a caution. Paroxetine and fluoxetine also reduce hot flashes, but they block an enzyme tamoxifen needs to become its active form. The 2023 review says they shouldn't be prescribed with tamoxifen, and the British Menopause Society says most guidelines agree, though one is less strict. The NCI cites a Canadian study of more than 2,400 women linking paroxetine plus tamoxifen to a higher risk of death. Make sure anyone prescribing you an antidepressant knows you take tamoxifen.
Gabapentin. A nerve-pain and seizure medicine that the NCI says reduces hot flashes by about 55 to 60 percent. It's usually started as a bedtime dose. Sleepiness, dizziness and trouble concentrating are the common downsides.
Oxybutynin. A bladder medicine used "off label" for hot flashes. In a Mayo Clinic-led trial where about two-thirds of the women were on tamoxifen or an aromatase inhibitor, the higher dose cut hot flashes by about 86 percent, compared with 27 percent on placebo, over six weeks. Dry mouth was the main side effect. The study was short, and long-term effects on thinking weren't studied.
Clonidine. A blood pressure drug that reduces hot flashes by about 40 percent, per the NCI. It's less effective than the options above.
The newer drugs. Fezolinetant (Veozah) and elinzanetant (Lynkuet) are non-hormonal pills that block neurokinin receptors. Both are FDA-approved for menopausal hot flashes, but as of October 2026 neither U.S. approval specifically covers women on breast cancer hormone therapy. A trial of elinzanetant in 474 women on hormone therapy for breast cancer found fewer daily hot flashes than placebo, and in September 2026 the FDA gave that use priority review. The UK already licenses it for these hot flashes. A large fezolinetant trial in the same group has finished enrolling, with results not yet in the sources we checked. Fezolinetant carries an FDA boxed warning for rare but serious liver injury and requires regular blood tests.
Hypnosis. In one trial of postmenopausal women without cancer, the NCI reports, hypnosis cut hot flashes by 75 percent at 12 weeks. A separate study found it helped women after breast cancer, the British Menopause Society says.
Cognitive behavioral therapy. This short, structured talk therapy makes hot flashes less bothersome, the NCI says, though not less frequent. It works best alongside other treatment.
Acupuncture. The evidence is mixed. A 2016 review of trials in breast cancer patients found little or no effect, while a trial in 120 women after breast cancer found electroacupuncture worked best of the options tested. Real acupuncture often does about as well as sham, the British Menopause Society notes.
Supplements. Most studies show soy and black cohosh do no better than placebo, the NCI says, and the British Menopause Society advises avoiding black cohosh with tamoxifen. Tell your team about anything you take.
Why can't most women with breast cancer take hormone replacement for hot flashes?
Estrogen is the most effective treatment for menopausal hot flashes, the NCI notes, but many women with breast cancer can't take it. Estrogen combined with progestin may raise the risk of breast cancer or of it coming back. Breast cancer hormone therapy works by taking estrogen away; standard hormone replacement puts it back. Low-dose vaginal estrogen for dryness is a separate conversation that some guidelines allow in certain cases.
What can you do tonight to manage hot flashes and night sweats?
Dress in layers of cotton or linen, which pull moisture away and dry fast. Sleep on cotton sheets.
Keep cool within reach: cold water, a hand fan, a small fan by the bed. Dana-Farber suggests a cool shower before bed and one foot out from under the covers.
Act at the first flush: cold water on your face or hands, or a cold, wet washcloth on the back of your neck.
Learn your triggers. Dana-Farber lists spicy food, alcohol, caffeine, smoking, hot showers, hot tubs, saunas, hot weather and stress. Everyone's list differs, so a few days of notes help. Regular exercise may also help.
Why you shouldn't stop hormone therapy on your own because of hot flashes
It's tempting to skip doses when you're soaked at 3 a.m. But hormone therapy is usually prescribed for at least five years, and consistency matters. In a study of nearly 8,800 Kaiser Permanente patients, 31 percent stopped early, and stopping early was linked to a higher risk of death. Tell your team how bad it is. They can treat the side effect or switch you to a different drug.
When to call your care team about hot flashes or hormone therapy side effects
- Hot flashes, night sweats or joint pain bad enough that you're thinking about stopping your medicine
- Night sweats that wreck your sleep night after night
- Any unusual vaginal bleeding or discharge, or pelvic pain, if you take tamoxifen
- Swelling or tenderness in one leg, if you take tamoxifen
- A new breast lump
- Yellow skin or eyes, dark urine, pale stools or pain in the upper right belly, if you take fezolinetant
Chest pain, sudden shortness of breath, or sudden weakness, numbness, confusion or trouble speaking need care right away. If it feels like an emergency, call 911.
Questions to ask your care team about hot flashes on hormone therapy
- Are my hot flashes typical for the drug I'm on, and might they ease with time?
- Which non-hormonal treatment would you try first for me, and would CBT or hypnosis help too?
- Does anything I take, including antidepressants or supplements, interact with my hormone therapy?
- Would oxybutynin, gabapentin or one of the newer drugs be an option for me?
- If I can't tolerate this drug, what are my alternatives?
- What can I do about joint pain or vaginal dryness?
If treatment is over but you still don't feel like yourself, read I Finished Treatment. Why Don't I Feel Better?. Tired all the time, too? Read Treatment Is Over. Why Am I Still This Tired?
Sources: National Cancer Institute, Hot Flashes and Night Sweats (PDQ), Patient Version (updated February 2025) and Health Professional Version (updated January 2025). American Cancer Society, Hormone Therapy for Breast Cancer. British Menopause Society, Non-hormonal-based treatments for menopausal symptoms (amended July 2026). Kim C, et al. A Recent Review of the Management of Postmenopausal Symptoms in Breast Cancer Survivors. Journal of Menopausal Medicine, December 2023. Dana-Farber Cancer Institute, Young and Strong Program, Hot flashes and excessive sweating; Adult Survivorship Program, Vasomotor Symptoms. The ASCO Post, Oxybutynin for Managing Hot Flashes (January 2019). U.S. Food and Drug Administration, Veozah liver injury warning (current as of April 2026). ClinicalTrials.gov, NCT06440967. Targeted Oncology, elinzanetant priority review (September 2026). Contemporary OB/GYN, FDA approves elinzanetant (October 2025). Hershman DL, et al. Early discontinuation and non-adherence to adjuvant hormonal therapy are associated with increased mortality. Breast Cancer Research and Treatment, 2011. MedlinePlus, Tamoxifen. This article is general information, written in Babette's own words, and is not a substitute for advice from your care team.
